This invention relates to an antenna unit and a feeding component included therein, particularly, to a satellite signal receiving antenna unit for receiving a circular polarized wave such as a satellite radio broadcast.
A GPS (Global Positioning System) receiving antenna is currently known as an example of an antenna for receiving a radio wave from an artificial satellite. As the GPS receiving antenna, what is called a patch antenna is used, for example. The patch antenna has a ceramic board, which is an insulating material, with a pair of main surfaces On one of the main surfaces of the ceramic board, a ground electrode is provided. On the other of the main surfaces of the ceramic board, a receiving electrode and a feeding pin are provided. The feeding pin is used for supplying a receiving signal to an external circuit.
Recently, it is propelled to execute a radio broadcast and so on using a circular polarized wave transmitted from the artificial satellite. To receive the radio broadcast, what is called a satellite radio broadcast receiving antenna is used.
The satellite radio broadcast receiving antenna includes a feeding component and a metal plate (or a ground electrode) on which the feeding component is mounted. The feeding component includes a feeding line and an attaching member for supporting the feeding line against the metal plate.
The attaching member has a pair of fixing tongues which has locking hooks and protrudes downward. On the other hand, the metal plate provides a pair of locking aperture to partly receive the fixing tongues. When the attaching member is mounted on the metal plate, the fixing tongues are partly inserted in the locking aperture and the locking hooks engage with edges defining the locking apertures. As a result, the attaching member is fixed to the metal plate. In this time, the locking hooks are projected downward from a rear surface of the metal plate.
The feeding component is connected to a circuit board which is placed on the rear surface of the metal plate. To miniaturize the antenna unit, it is desirable that the circuit board is located to be close to the rear surface of the metal plate. However, as mentioned above, the locking hooks of the attaching element are projected from the rear surface of the metal plate. Accordingly, it is necessary to locate the circuit board to avoid collision with the locking hooks projected from the rear surface of the metal plate. Therefore, the satellite radio broadcast receiving antenna has a problem that the circuit board has limited shape and its mounting area is small.